Player evaluation is not an exact science. For every Peyton Manning, there is a Ryan Leaf. For every first-round star, there's a first-round bust. There is also a long list of players who slip through the cracks and become stars despite not being drafted high.

Tom Brady is the poster boy for late-round NFL Draft steals. The former Michigan quarterback was selected in the sixth round by the Patriots in the 2000 draft and has since won four Super Bowls, played in two others, was the league MVP twice and selected to 10 Pro Bowls.

Former Packers quarterback Bart Starr (17th round, 1956) and former Colts quarterback Johnny Unitas (ninth round, 1955) won multiple championships and were both inducted into the Pro Football Hall of Fame.

Two of the most feared defensive linemen of the 1960s were late-round selections — Deacon Jones and Willie Davis. Jones was taken in the 14th round of the 1961 draft out of Mississippi Valley State — the same school that produced wide receiver Jerry Rice. Jones then went on to lead the Rams' famed Fearsome Foursome while coining the term "sack" and was a 1980 Hall inductee. Davis, a 1981 Hall of Fame selection, was a 15th-round pick by the Browns in the 1956 draft before helping the Packers win five NFL titles in the 1960s.

Larry Wilson was a seventh-round selection by the Cardinals and in 1960 and retired 12 years later as the franchise's all-time leader with 52 interceptions, a record he still holds.

Back in 1953, the Giants selected Morgan State offensive lineman Roosevelt Brown, who helped anchor a unit that played for the NFL championship six times. He was inducted into the Pro Football Hall of Fame in 1975.

Tyler Varga, Yale: Varga may be from the Ivy League, but he was one of the stars at the Senior Bowl. Varga can be a solid H-back in the NFL for years to come.

Zach Zenner, South Dakota State: Zenner is a running back in a fullback's body. The 6-0, 220-pound Zenner is the only player in NCAA Division I history to rush for more than 2,000 yards in a season three times. He also caught 95 passes in college.

John Crockett, North Dakota State: While helping lead the Bison to four straight FCS national championships, Crockett set single-season school records last year with 2,419 total yards and 1,994 on the ground. He's a physical runner with 4.5 speed to go with a 6-0, 217-pound body.

Wide receiver

Stefon Diggs, Maryland: Diggs has battled through injuries, but when healthy, he's explosive with his 4.4 speed. He is also a dangerous return man.

Justin Hardy, East Carolina: The NCAA's all-time leading receiver compares favorably to Wes Welker and could have a similar career.

Jamison Crowder, Duke: Crowder is small, but he's one of the fastest receivers in a very deep draft class. Speed kills and Crowder could be a scoring assassin.

Rashad Greene, Florida State: A Biletnikoff Award semifinalist, the 5-11, 182-pound Greene set a single-season school record last year with 99 receptions.

Cam Worthy, East Carolina: While Hardy was ECU's go-to guy, Worthy was Carden's deep threat. If he comes back from a foot injury healthy, the 6-2, 211-pound Worthy can be catching a plethora of jump balls on Sunday.

Tight end

MyCole Pruitt, Southern Illinois: Outside of Minnesota's Maxx Williams, Pruitt might be the best athlete at the position.

Nick Boyle, Delaware: Boyle was a star at the Senior Bowl, showing surprising athleticism, and can be a reliable receiver for many years in the NFL.

Ben Koyack, Notre Dame: At 6-5, 255, Koyack has the size of an NFL tight end. If he can develop more as a receiver, he'll do well at the next level.

Blake Bell, Oklahoma: A former quarterback, Bell understands route concepts but is also big and strong. He's raw at the position but has tremendous upside.

Devin Mahina, BYU: Mahina doesn't have great hands and isn't a great blocker but he is an excellent athlete who could develop into a complete NFL tight end.

Offensive linemen

T.J. Clemmings, T, Pittsburgh: Clemmings was thought to be a first-round talent, so the fact that some team could get him on Day 3 is a big surprise.

La'el Collins, T, LSU: Less than a week ago, Collins was a first-round lock, but then his name surfaced as part of a murder investigation. If/when he's free and clear of that, teams will be lining up for his services.

B.J. Finney, C, Kansas State: Finney is a former walk-on who ended up as a four-year starter. He's a high-motor former wrestler with 52 college starts and the drive to succeed. While not the most fluid athlete, Finney is as reliable as they come and has sound technique.

Arie Kouandjio, G, Alabama: The brother of Bills lineman Cyrus Kouandjio, Arie is not quite the athlete that Cyrus is, but he is big and strong and has a good understanding of blocking schemes.

Tre Jackson, G, Florida State: If Jackson gets a shot and can prove his work ethic is sound, the talent and physical qualities are there.

Defensive linemen

Grady Jarrett, Clemson, DT: Jarrett anchored what was a very good defensive line on the nation's top defense last year. Thought to be a second-round prospect, Jarrett would be an ideal fit in the middle of a 4-3 defense.

Michael Bennett, Ohio State: Another second-round prospect who slipped to Day 3, Bennett was a two-time All-Big Ten selection and has the potential to be a solid starter in the NFL.

Za'Darius Smith, Kentucky, DE: A junior college transfer, Smith never missed a game at UK as he played opposite first-round pick Bud Dupree. Smith was the defensive MVP of the East-West Shrine Game and played well at the Senior Bowl. He's a high-motor player who can fit nicely into a 4-3 end rotation.

Rakeem Nunez-Roches, Southern Miss, DT: A 6-2, 307-pound mass of muscle, Nunez-Roches has short arms, but relentless effort that NFL coaches will love.

Linebacker

Kwon Alexander, LSU: The Tigers' leading tackler last year, Alexander has good speed and plays well sideline to sideline.

Ben Heeney, Kansas: When you are a three-time all-conference selection as a Kansas football player, you're doing something right. Heeney, simply put, is a damn good player whom coaches love.

Bryce Hager, Baylor: A three-year starter for the Bears, Hager was a tackling machine and could play for a long time as some team's middle linebacker.

Davis Tull, Chattanooga: A three-time Southern Conference Defensive Player of the Year, Tull runs a 4.5 and plays all over the field. He has a nose for the ball and excellent instincts.

Kyle Emanuel, North Dakota State: The 2014 Missouri Valley Conference Defensive Player of the Year also earned first-team All-American honors last season. A former running back, Emanuel was a four-year starter at linebacker for NDSU and put up gaudy numbers.

Ramik Wilson, Georgia: A two-time All-SEC selection, Wilson led the conference with 133 total tackles as a junior and then had 110 tackles as a senior. He also collected 18 tackles for loss and six sacks the past two seasons.

Defensive backs

Ifo Ekpre-Olomu, Oregon: Ekpre-Olomu would've been the top corner in the draft had he not suffered a knee injury during the Rose Bowl. He'll get drafted at some point Saturday and may have a redshirt rookie season, but if he can return to form, he could have multiple Pro Bowl seasons.

Kurtis Drummond, Michigan State: A three-year starter and two-time All-Big Ten selection, Drummond has great size for a safety (6-1, 208) and good ball skills. If he can improve his tackling, he will be a stalwart in an NFL secondary.

Gerod Holliman, Louisville: Holliman knows how to find the ball; he led the NCAA with 14 interceptions last year. The Thorpe Award winner is only 20 years old and is not yet a finished product.

Chris Hackett, TCU: A three-year starter for one of the nation's top defenses, Hackett is a solid tackler despite his thin frame (6-0, 195). He's more quick than fast and has good instincts.

Adrian Amos, Penn State: A three-year regular with 37 starts to his name, Amos has 4.3 speed, something you don't see often from a free safety. He's also a smart player, which helps him get to any spot on the field.

Ibraheim Campbell, Northwestern: An aggressive four-year starter for the Wildcats, Campbell is an intelligent box safety who could be a special teams anchor. He must remain healthy, though.

Deshazor Everett, Texas A&M: He's tough. He's smart. He plays hard. He's a football player. Everett may go late in the draft, but he also might end up on someone's roster for a long time once he shows his effort and ability in camp.